Sixth Senses

We’ve all heard about “the five senses”—sight, taste, touch,
smell, and hearing. But are there other ways to experience the world? Yes, it
turns out that God designed certain animals with “super senses” that make us
look weak in comparison!

How Do You Experience the World?

In a thunderstorm you can watch the rain pelting the neighbors’ rooftops, while
you sniff the damp dirt, hear the crackling thunder, taste the moist air, and
revel in the water running down your face. A simple rain shower can engage all
five senses. With each sense we can experience the wonderful world God has made,
for we know “the hearing ear and the seeing eye, the Lord has made them both”
(Proverbs 20:12). We rely on our senses to tell us accurately
about our surroundings. However, our five senses cannot detect everything. The
world is full of information beyond our reach, but many animals have “sixth
senses”—super senses that enable them to experience other dimensions of our
world. These bonus senses help these creatures survive and thrive in their habitats.

Motion Sensors

One special sense is called mechanoreception. This sense allows web-spinning
spiders to perceive minute pressure on their exoskeleton. Spiders have specialized
organs called slit sensilla. These organs are small grooves at the spider’s
joints, which change shape under stress. As the spider sits on its web, the
slightest movement on the strand causes a slit to change shape, and mechanoreceptors
in the slit detect the change.

The slit sensillum is so precise that the spider can determine the creature’s
size and weight, or establish if the strain was just a passing breeze. The slit
sensillum and other special senses are possibly as important for survival as
the spider’s own eyes.

Sonic Sensors

Animals that fly by night and can’t rely on vision need an alternative way
to navigate safely without relying on their eyes. Bouncing sound waves off nearby
objects is a handy way to move around if you have the right equipment. Bats
do, and scientists are still uncovering new surprises about the complex, interacting
components that must all be in place for this system to work.

Photo: Dreamstime.com

Bats rely on complex echolocation to maneuver in the dark.

Two things are needed to see with your ears (a phenomenon more commonly known
as echolocation): a sound producer and a sound receiver. Bats use their vocal
cords to produce sound waves, controlling the intensity, direction, and frequency.
This sound is loud enough to easily bounce off any object, whether moving or
stationary, and return to the bat.

The sound receivers, the bat’s ears, may be the most interesting parts of the
echolocation system. Bats have complete control over which sounds their ears
pick up. Otherwise, their highly sensitive ears would go deaf whenever they
made their loud, high-frequency sounds.

So when the bat produces sound, either it uses its middle-ear muscles to close
its ears or it adjusts them to hear only a certain frequency. As the sound waves
bounce back toward the bat, the frequency shifts, due to something called the
Doppler Effect. This allows the bat to protect its ears from the loud frequency
going out while retaining the ability to hear other frequencies coming in.

Magnet Sensors

But not all animals live in the dark. Even when your world is full of light,
it can be difficult to find your way. Another impressive method of navigation,
used by pigeons, is called magnetoreception. Homing pigeons can detect the earth’s
magnetic field and use it as a map to find their way home.

Photo: Dreamstime.com

Pigeons can navigate their way back home using magnetoreceptors located at the base
of their beaks.

In flight, there are three dimensions to account for: left and right, up and
down, and forward and backward. Like other birds, pigeons are known for their
excellent eyesight. Most of their navigation can be handled by landmarks and
other visual cues. However, when they are put in a cage and transported to a
strange location, how do they manage to find their way home?

Though scientists have yet to determine precisely how pigeons respond to the
earth’s magnetic field, they have found many clues. The most promising hint
is in their spectacular beaks. Along the skin lining of their upper beak are
iron-containing particles called magnetite. The magnetite is attached to nerve
endings arranged in a complex, three-dimensional pattern.

This three-dimensional spread is the key to creating a three-dimensional map
of the world. The earth’s magnetic field moves in three dimensions, and the
pigeon can detect it in all three directions. The details still are uncertain,
but it is assumed that the sensory cells associated with the magnetite (called
magnetoreceptors) sense slight changes in the angle of the magnetic field, enabling
the pigeon to find its way home.

Electricity Sensors

Looking for changes in magnetism isn’t the only way animals can sense the environment.
Sharks, as well as many other vertebrates that live in the water, can locate
other creatures with the aid of electroreception. This means they can detect
electrical impulses.

When a fish moves, its brain sends out a tiny nerve impulse to the muscles
that contract. Those impulses create an electric field that extends into the
water and can be detected.

Sharks detect these bioelectric fields with their ampullae of Lorenzini. The
ampullae look like black pores on the shark’s snout. These pores are distributed
symmetrically across the shark’s head, allowing the shark to easily determine
the direction where the electric field originated. Each pore is full of sensory
cells surrounded by a specialized jelly. When exposed to a bioelectric field,
the sensory cells are stimulated, alerting the shark to a potential food source.

Electroreception is found typically in animals that live in salt water. Even
if humans had the ability to detect electric fields emanating from contracting
muscles, it probably wouldn’t be very sensitive. Air isn’t a very good medium
for carrying electric fields. However, salt water is because it has a higher
concentration of ions.

Sharks have the most sensitive electroreception abilities in the animal kingdom.
They can detect an electric field as weak as five billionths of a volt per centimeter, which
is significantly weaker than the electric field produced by a ticking wristwatch.

Heat Sensors

Photo: Dreamstime.com

Pit vipers detect
heat using specialized pit organs located between the eyes
and nostrils.

Many sixth senses help animals find food. For example, snakes known as pit
vipers and pythons, as well as some boas, use infrared detectors called pit
organs. On pit vipers these organs look like an extra pair of nostrils between
the eyes and nostrils, but on pythons and most boas the pits are located on
the upper lip. These specialized pit organs can “see” infrared radiation.

Every object with a temperature above absolute zero has heat. Some of the heat
is emitted as infrared radiation, a type of light that cannot be seen with the
naked eye. Heat receptors at the back of the pit organ detect infrared much
the same way that photoreceptors (rods and cones) in your eye detect visible
light. Pit organs detect temperature variations with great precision, as little
as 0.0054°F (0.003°C).

Pit vipers often hunt at night, waiting for warm-blooded prey to pass by. Since
animals give off infrared light, the snake can “see” with its pit organs, even
in the dark. While pit organs are useful in today’s fallen world, they were
not needed for this purpose before the Fall. Perhaps the vipers’ sixth sense
aided in locating ripe fruit in the dark, though this is conjecture. (Ripe fruit
emits infrared radiation up to a degree hotter than the surrounding plants,
and rotten fruit is even hotter.)

Another possibility is that pit vipers used their pit organs to find warm resting
spots, where they could absorb heat. Since they are cold-blooded, they cannot
generate their own body heat through metabolism.

Since snakes no longer consume warm fruit, they need help from several senses
to distinguish food from warm but inedible objects. Pit vipers don’t want to
bite warm rocks! Amazingly, they can ignore background infrared radiation (from
rocks and other inedible sources). This is partly due to a skill called adaptation,
the ability to ignore certain unchanging stimuli. Your skin relies upon this
skill as well. Your brain is not always conscious of the clothes touching your
body unless something changes significantly in the texture, pressure, or weight.
Similarly, the pit viper is alerted by movement and contrasting temperatures.
When a warm-blooded mouse wanders by, it sticks out like a sore thumb against
the cooler background.

Distinguishing heat sources is a bit difficult, so many pit vipers prefer to
find a cooler place to sit and wait for dinner to come by. This explains why
they often hunt at night, when it is cooler and the prey’s warm body stands
out more sharply.

Handiwork of the Creator

These bonus senses might sound like science fiction, but God has designed the
animal kingdom to exhibit these wonders abundantly every day. No incremental
changes over millions of years could ever account for these astounding sensors,
which work in perfect sync with the brain.

Each extra sense is every bit as complex as the traditional five. Just as the
components of the eye could not spontaneously arise in stages through evolution,
these complex senses could not arise without a Master Craftsman. The Creator’s
handiwork, around six thousand years ago, gave these animals the ability to
experience this world in a way we never have. But who knows, maybe we will someday
. . . in our resurrection bodies!

Heather Brinson Bruce earned dual degrees in English and chemistry from Clemson University. She write for Answers magazine as a freelance author.

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Answers Magazine

January – March 2013

Learn about our culture's newest tactics in the battle for kids' souls, and discover what you can do in your home and church to reclaim our youth for Jesus, the Creator. In addition to this special section of three articles, you'll find all the creation content you expect from Answers magazine, including a look at Lucy, the famous ape; animals with "sixth senses"; ancient and modern reefs; and intriguing findings about the animal kinds on Noah's Ark.

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